CN113395516A

CN113395516A - Intra-frame prediction method and device and computer-readable storage medium

Info

Publication number: CN113395516A
Application number: CN202110708337.8A
Authority: CN
Inventors: 霍俊彦; 马彦卓; 万帅; 杨付正; 郭锦坤
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2019-01-02
Filing date: 2019-01-02
Publication date: 2021-09-14
Anticipated expiration: 2039-01-02
Also published as: EP3890317A4; JP7439219B2; US20240223805A1; US20220232251A1; CN116647675A; WO2020140217A1; US20220232252A1; JP2023018019A; KR20210100728A; EP3890317A1; JP2022516624A; US11805276B2; US20220232250A1; US11962802B2; CN116437080A; JP7181412B2; EP4290862A3; US11856153B2; CN112956191A; CN113395516B

Abstract

An intra prediction method and apparatus, and a computer storage medium, comprising: configuring an actual angle mode represented by a relative angle number; the relative angle numbers sequentially represent the corresponding actual angle modes after sampling by adopting preset angle sampling points from an initial angle within a prediction direction range corresponding to a preset width-height relationship; the starting angle is determined according to the width-height relationship of the processing block and the prediction direction range corresponding to the preset width-height relationship, and the actual angles correspond to the actual angle modes one by one.

Description

Intra-frame prediction method and device and computer-readable storage medium

The application is a divisional application of an application with the application date of 2019, 1, 2 and the application number of 2019800712115, and the name of the invention is 'intra-frame prediction method and device and computer-readable storage medium'.

Technical Field

Embodiments of the present disclosure relate to intra prediction technologies in the field of video coding, and in particular, to an intra prediction method and apparatus, and a computer storage medium.

Background

In order to reduce the number of bits for entropy Coding in the luma prediction process of the next generation Video Coding standard h.266 or multi-function Video Coding (VVC), an MPM list is constructed to store the prediction modes of neighboring blocks. Based on the principle that the similarity of spatial neighboring blocks is high, the prediction mode selected by the current block has a high probability to be the same as a certain mode existing in the MPM list, and therefore, the prediction mode of the current block can be encoded by using a smaller number of bits. However, due to the existence of the non-square angular mode, the actual angular direction represented by the angular mode number may be different from the original meaning, which results in that the angular mode with the same number in the MPM list may represent different prediction directions for the neighboring block and the current block, and the situation classification is numerous, which may affect the accurate representation and use of the prediction mode of the current block. In addition, in the chroma prediction process, the DM mode may use the prediction mode of the luma block at the center of the current chroma block, and the DM mode may use the original angle mode number no matter whether the prediction mode of the luma block is the wide angle mode, which may cause a deviation between the angle mode actually used by the chroma block and the angle mode of the corresponding luma block. That is to say, in the wide angle mode, the angle mode numbers may correspond to different actual angle modes, so that the angle conversion is more complicated in the luminance prediction process, and the angle mode of the luminance block borrowed for chrominance prediction also has a deviation, resulting in the problem of inaccurate prediction.

Disclosure of Invention

The embodiment of the application provides an intra-frame prediction method and device and a computer readable storage medium, which can effectively improve the accuracy of intra-frame prediction and improve the coding and decoding efficiency.

The technical scheme of the embodiment of the application is realized as follows:

the application provides an intra prediction method, which comprises the following steps:

configuring an actual angle mode represented by a relative angle number; the relative angle numbers sequentially represent the corresponding actual angle modes after sampling by adopting preset angle sampling points from an initial angle within a prediction direction range corresponding to a preset width-height relationship; the starting angle is determined according to the width-height relationship of the processing block and the prediction direction range corresponding to the preset width-height relationship, and the actual angles correspond to the actual angle modes one by one.

In the above scheme, when the sampling of the preset angle sampling point is 65, the relative angle numbers are consecutive numbers in a range from 2 'to 66', the actual angle patterns corresponding to the relative angle numbers are 65 consecutive actual angle patterns in a range from-14 to 80, and the selection of the 65 actual angle patterns is determined by a width-height relationship, wherein the relative angle numbers and the actual angle patterns correspond one to one in sequence.

In the above scheme, when the sampling of the preset angle sampling point is 33, the relative angle numbers are consecutive numbers in a range from 2 'to 34', the actual angle patterns corresponding to the relative angle numbers are 33 consecutive actual angle patterns in a range from-7 to 41, and the selection of the 33 actual angle patterns is determined by a width-height relationship, wherein the relative angle numbers and the actual angle patterns correspond one to one in sequence.

In the above scheme, when the sampling of the preset angle sampling point is 129, the relative angle numbers are consecutive numbers in a range from 2 'to 130', the actual angle patterns corresponding to the relative angle numbers are 129 actual angle patterns consecutive in a range from-28 to 158, and the selection of the 129 actual angle patterns is determined by a width-height relationship, wherein the relative angle numbers and the actual angle patterns correspond one to one in sequence.

The embodiment of the present application further provides an intra prediction method, including:

acquiring a width-height relation of a reference block of a current block, a prediction direction range corresponding to a preset width-height relation and a preset angle sampling point;

determining an actual angle mode corresponding to the reference block represented by a relative angle number according to the width-height relationship, the prediction direction range corresponding to the preset width-height relationship and the preset angle sampling point, so that the actual angle corresponds to the actual angle mode one by one;

obtaining an angle prediction mode corresponding to the reference block based on the actual angle mode corresponding to the reference block;

intra-predicting the current block based on the angular prediction mode.

In the foregoing solution, the determining, according to the width-height relationship, the prediction direction range corresponding to the preset width-height relationship, and the preset angle sampling point, an actual angle mode corresponding to the reference block indicated by a relative angle number includes:

determining an initial angle of an angle mode of the reference block according to the prediction direction range corresponding to the width-height relationship and the preset width-height relationship;

determining an angle offset range of the reference block based on the preset angle sampling point;

and determining the actual angle mode corresponding to the reference block represented by the relative angle number according to the starting angle and the angle deviation range.

In the above solution, the intra-predicting the current block based on the angular prediction mode includes:

constructing a prediction mode list of the current block based on the angular prediction mode;

and adopting a prediction mode list to realize intra-frame prediction of the current block.

In the above scheme, the intra prediction includes at least one of: luma intra prediction and chroma intra prediction.

An embodiment of the present application provides an intra prediction apparatus, including:

the system comprises a processor, a memory storing processor-executable intra-frame prediction instructions, and a communication bus for connecting the processor and the memory, wherein the intra-frame prediction instructions, when executed, realize the intra-frame prediction method.

The embodiment of the application provides a computer readable storage medium, on which the intra-frame prediction instruction is stored, wherein the intra-frame prediction instruction is executed by a processor to realize the intra-frame prediction method.

In the embodiment of the application, by adopting the technical implementation scheme, the intra-frame prediction device can process reference blocks with different width-height relationships in the intra-frame prediction process by adopting a uniform actual angle mode, so that the actual angles correspond to the actual angle modes one by one, and therefore, when a certain angle is represented in the luminance prediction process or the chrominance prediction process, the angle mode of each block in each shape is specifically determined according to the length-width ratio, the angle conversion in the wide-angle mode is simplified, the meaning of the angle value represented by each mode is unified, the deviation is eliminated, the accuracy of intra-frame prediction is effectively improved, and meanwhile, the coding and decoding efficiency is improved.

Drawings

FIG. 1 is a diagram illustrating the VVC supporting 67 intra prediction modes according to an embodiment of the present invention;

fig. 2A is a schematic structural diagram of a video coding system according to an embodiment of the present application;

fig. 2B is a schematic structural diagram of a video decoding system according to an embodiment of the present application;

FIG. 3 is a diagram illustrating exemplary intra prediction modes for wide angle mode provided by an embodiment of the present application;

fig. 4 is a flowchart of an intra prediction method according to an embodiment of the present application;

FIG. 5 is a diagram illustrating exemplary neighboring intra prediction modes provided by an embodiment of the present application;

fig. 6 is a first schematic diagram illustrating an arrangement of a luminance block and a chrominance block corresponding to a current block according to an exemplary embodiment of the present disclosure;

fig. 7 is a second schematic diagram illustrating an arrangement of a luma block and a chroma block corresponding to a current block according to an exemplary embodiment of the present disclosure;

fig. 8 is a first schematic structural diagram of an intra prediction apparatus according to an embodiment of the present disclosure;

fig. 9 is a schematic structural diagram of an intra prediction apparatus according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant application and are not limiting of the application. It should be noted that, for the convenience of description, only the parts related to the related applications are shown in the drawings.

The title in this application is explained first.

VVC/H.266 is the next generation video coding standard.

VTM: the Test Model of VVC is a Test platform of The reference software of VVC.

MPM, Most Probable Modes.

DM: direct mode, a chroma prediction mode.

VER: the vertical direction angle prediction mode corresponds to the intra prediction mode number 50 in VTM 3.0.

HOR: the horizontal direction angle prediction mode corresponds to the intra prediction mode numbered 18 in VTM 3.0.

DIA: the diagonal direction angle prediction mode corresponds to the intra prediction mode numbered 34 in VTM 3.0.

VDIA: the anti-diagonal direction angle prediction mode corresponds to the intra prediction mode numbered 66 in VTM 3.0.

In the embodiment of the present application, the functions of predictive coding are: in video coding, the predicted value of the current block is constructed by using the existing reconstructed image in space or time, and only the difference value between the original value and the predicted value is transmitted, so as to achieve the purpose of reducing the transmission data volume. In the brightness prediction, the original value and the predicted value can be the original value of the brightness and the predicted value of the brightness; in chroma prediction, the original value and the predicted value here may be the original value of chroma and the predicted value of chroma.

The functions of intra prediction are: and constructing a prediction value of the current block by using a last line of pixel units and a left column of pixel units adjacent to the current block. Each pixel unit of the current block is predicted using neighboring pixels that have been restored around the current block, i.e., a pixel unit in the upper line adjacent to the current block and a pixel unit in the left column.

For example, a current block is a brightness block, when a brightness predicted value of the current block is constructed by using adjacent pixels, brightness prediction is sequentially performed on the current block by adopting multiple prediction directions to obtain a brightness predicted value matrix corresponding to each prediction direction; determining a difference value matrix corresponding to each prediction direction based on each brightness prediction value matrix and the brightness original value matrix of the current block; determining an evaluation parameter value corresponding to the prediction direction based on each difference matrix, wherein the evaluation parameter value is used for representing the prediction effect of the corresponding prediction direction on the current block; determining a target prediction direction from the multiple prediction directions based on each evaluation parameter value, for example, determining the prediction direction capable of obtaining the minimum image coding bit number as the target prediction direction on the premise of ensuring the video recovery quality; and then writing the target prediction direction into the code stream.

Illustratively, the VVC supports 67 intra prediction directions, i.e., prediction modes, wherein the index numbers 2-66 intra prediction directions are shown in fig. 1.

It should be noted that, in order to meet the demand of higher and higher video resolution and to express the direction of video content more finely and accurately, 33 intra luminance prediction angle modes defined in h.265/HEVC are expanded to 65 in h.266/VVC, and the new angle modes are indicated by dashed arrows in fig. 1. The number 0 indicates the Planar mode, the number 1 indicates the DC mode, and the numbers 2 to 66 indicate 65 angular modes (from bottom left to top right), for a total of 67 intra prediction modes, where 2 to 66 are absolute angular numbers.

In the embodiment of the present application, a method for constructing an intensity prediction value of each pixel unit of a current block is given by taking an intra prediction direction with an index of 66 as an example. Wherein, the previous line of data adjacent to the current block is a pixel unit for which prediction is completed. Each pixel unit of the current block is filled in units of pixels of the upper right diagonal line, i.e., the prediction direction of index number 66.

There are also two relatively flat structural prediction block schemes, each in DC mode PLANAR mode. The DC mode fills the entire current block with an average value of characteristic values (e.g., chrominance values or luminance values) of the previous line or left column, and the PLANAR mode fills the current block in a gradual manner.

For the luminance mode, prediction is performed sequentially according to 0-66 directions in fig. 1, a prediction direction that best matches (e.g., the difference is the smallest or the rate-distortion cost is the smallest) the current block is selected as a target prediction direction, and a luminance prediction value of each pixel unit of the current block is constructed, which is a basic principle of luminance intra-prediction. After the target prediction direction and the difference value corresponding to each pixel unit corresponding to the target prediction direction are obtained, the encoder writes the difference value corresponding to each pixel unit and the index number of the target prediction direction corresponding to the current block into the code stream. After the decoder receives the code stream, the received code stream is analyzed to obtain the index number of the target prediction direction, so that the brightness prediction value of each pixel unit in the corresponding current block can be calculated, and the brightness prediction value is added with the difference value analyzed by the code stream to obtain the brightness reconstruction value of the corresponding pixel unit.

Based on the above basic concepts, a video coding system is provided, and fig. 2A is a schematic structural diagram of a video coding system according to an embodiment of the present application, as shown in fig. 2A, the video coding system 21 includes:

a transform and quantization unit 211, an intra estimation unit 212, an intra prediction unit 213, a motion compensation unit 214, a motion estimation unit 215, an inverse transform and inverse quantization unit 216, a filter control analysis unit 217, a filtering unit 218, an encoding unit 219, and a decoded image buffer unit 210; for an input original video signal, a video reconstruction block can be obtained by dividing a Coding Tree Unit (CTU), and then, residual pixel information obtained by intra-frame or inter-frame prediction is transformed by a transformation and quantization Unit 211, including transforming the residual information from a pixel domain to a transform domain, and quantizing the obtained transform coefficient, so as to further reduce the bit rate; the intra estimation unit 212 and the intra prediction unit 213 are used to perform intra prediction on the video reconstructed block; the intra estimation unit 212 and the intra prediction unit 213 are configured to determine an optimal intra prediction direction (i.e., a target prediction direction) of the video reconstructed block; motion compensation unit 214 and motion estimation unit 215 are used to perform inter-prediction encoding of the received reconstructed block of video relative to one or more blocks in one or more reference frames to provide temporal prediction information; the motion estimation performed by the motion estimation unit 215 is a process of generating a motion vector that can estimate the motion of the video reconstructed block, and then, the motion compensation is performed by the motion compensation unit 214 based on the motion vector determined by the motion estimation unit 215; after determining the intra prediction direction, the intra prediction unit 213 is also configured to supply the selected intra prediction data to the encoding unit 219, and the motion estimation unit 215 also sends the calculated determined motion vector data to the encoding unit 219; furthermore, the inverse transform and inverse quantization unit 216 is used for reconstruction of the video reconstruction block, reconstructing a residual block in the pixel domain, which removes blocking artifacts through the filter control analysis unit 217 and the filtering unit 218, and then adding the reconstructed residual block to a predictive block in the frame of the decoded picture buffer unit 210 to generate a reconstructed video reconstruction block; the encoding unit 219 is configured to encode various encoding parameters and quantized transform coefficients, and in a CABAC-based encoding algorithm, context content may be based on neighboring reconstructed blocks, and may be configured to encode information indicating the determined intra prediction direction and output a code stream of the video signal; and the decoded picture buffer unit 210 is used to store reconstructed video reconstructed blocks for prediction reference. As the video encoding proceeds, new reconstructed video blocks are generated, and these reconstructed video blocks are stored in the decoded picture buffer unit 210.

Fig. 2B is a schematic structural diagram of a video decoding system according to an embodiment of the present invention, and as shown in fig. 2B, the video decoding system 22 includes:

decoding unit 221, inverse transform and inverse quantization unit 222, intra prediction unit 223, motion compensation unit 224, filtering unit 225, and decoded picture buffer unit 226; after the input video signal is coded by the video coding system 21, the code stream of the video signal is output; the code stream is input into the video decoding system 22, and first passes through the decoding unit 221 to obtain a decoded transform coefficient; the transform coefficients are processed by an inverse transform and inverse quantization unit 222 to produce a block of residual in the pixel domain; intra-prediction unit 223 may be used to generate prediction data for a current video decoded block based on the determined intra-prediction direction and data from previously decoded blocks of the current frame or picture; motion compensation unit 224 is a predictive block that determines prediction information for a video decoded block by parsing motion vectors and other associated syntax elements and uses the prediction information to generate the video decoded block being decoded; forming a decoded video block by summing the residual block from the inverse transform and inverse quantization unit 222 with the corresponding predictive block generated by the intra prediction unit 223 or the motion compensation unit 224; the decoded video signal passes through the filtering unit 225 to remove blocking artifacts, which may improve video quality; the decoded video blocks are then stored in a decoded picture buffer unit 226, and the decoded picture buffer unit 226 stores reference pictures for subsequent intra prediction or motion compensation, and also for output of the video signal, resulting in a restored original video signal.

The embodiment of the present application mainly acts on the intra prediction unit 213 of the video encoding system 21 and the intra prediction unit 223 of the video decoding system 22; that is, if the video encoding system 21 can obtain a better prediction effect by the intra prediction method provided in the embodiment of the present application, the video decoding recovery quality can be improved at the decoding end correspondingly.

Based on this, the technical solution of the present application is further elaborated below with reference to the drawings and the embodiments.

It should be noted that, an intra prediction apparatus provided in the embodiment of the present application may be an encoder or a decoder, and the embodiment of the present application is not limited thereto.

An embodiment of the present application provides an intra prediction method, which may include:

configuring an actual angle mode represented by a relative angle number; the relative angle numbers are sequentially represented in a prediction direction range corresponding to a preset width-height relationship, and a corresponding actual angle mode is sampled by adopting a preset angle sampling point from an initial angle; the starting angle is determined according to the prediction direction range corresponding to the width-height relation of the processing block and the preset width-height relation, and the actual angles correspond to the actual angle modes one by one.

The embodiment of the application provides an intra-frame pre-side method, which relates to a process of writing a pre-side number of a prediction mode of a current block into a code stream for coding and decoding.

The wide angle mode is explained below with 65 kinds of angle intra prediction modes. Wide angle mode: the prediction directions of the 65 angular intra prediction modes as shown in fig. 1 are defined to be 45 degrees (mode 66) to-135 degrees (mode 2) in the clockwise direction. Considering that a QTBT coding block division structure is added into the H.266/VVC, some non-square coding blocks are generated. For non-square coded blocks, several conventional angular intra prediction modes will be replaced with the extended wide angle mode. The number of conventional angle patterns to be replaced is related to the aspect ratio of the current coding block, and the larger the ratio, the more conventional angle patterns need to be replaced by wide angle patterns.

There are 85 angular orientations patterns in VTM2.0.1, and DC and Planar patterns, where 20 angular orientations are out of the range between-135 degrees and 45 degrees, i.e., wide angles. Angular directions within-135 degrees (mode 2) to 45 degrees (mode 66) in the clockwise direction are designed for the square and encompass the diagonal directions (

modes

2, 34 and 66) of all the square blocks. However, it is not always possible for a non-square block to cover its diagonal direction. In addition, the angular direction of the square block is from the lower left diagonal direction to the upper right diagonal direction, but not the angular direction of the square block.

As shown in fig. 3, there are 93 angular direction modes and DC and Planar modes, where 28 angular directions are beyond the range between 45 degrees and-135 degrees, i.e., wide angles.

A unified wide-angle model proposed by the L0279 proposal is accepted in the latest h.266/VVC reference software VTM3.0, which proposes a three-point improvement:

limiting the angular mode of the current coding block from the lower left diagonal direction to the upper right diagonal direction;

limiting the wide-angle mode expanded by the current coding block to always comprise the diagonal directions of the left lower part and the right upper part;

the reference ranges are uniform, 2 × W +1 for the upper reference range and 2 × H +1 for the left reference range.

Where W is the width of the block (encoded or decoded block) and H is the length of the block (encoded or decoded block).

It should be noted that the unified approach proposed by the L0279 modifies the number of conventional patterns that need to be replaced with wide angle patterns, so that the angular range after the wide angle is expanded is just between the lower left diagonal direction and the upper right diagonal direction (e.g., between 2 and 66), as shown in table 1. Meanwhile, the method also properly modifies the direction of the expanded wide-angle mode and the direction of the traditional angle mode which needs to be replaced, so that the diagonal direction of the current coding block under various aspect ratios is included.

TABLE 1

Coding block width-height relationship	Conventional intra mode that needs to be replaced with wide angle mode
		W/H＝＝2	Modes 2,3,4,5,6, 7-67, … …,72
W/H＝＝4	Modes 2,3,4,5,6,7,8,9,10, 11-67, … …,76
		W/H＝＝8	Molds 2,3,4,5,6,7,8,9,10,11,12, 13-67, … …,78
W/H＝＝16	Modes 2,3,4,5,6,7, … …,14,15 — 67, … …,80
		W/H＝＝0	Is free of
H/W＝＝2	Mode 61,62,63,64,65, 66- — 6, … …, -1
		H/W＝＝4	Modes 57,58,59, … …,64,65,66 — -10, … …, -1
H/W＝＝8	Modes 55,56,57,58,59, … …,65,66 — -12, … …, -1
		H/W＝＝16	Pattern 53,54,55,56,57,58, … …,66 — -14, … …, -1

Here, when the aspect ratio (or aspect ratio, the same applies hereinafter) is 2, there are 6 modes that need to be replaced; with an aspect ratio of 4, 10 modes need to be replaced; with an aspect ratio of 8, there are 12 modes that need to be replaced; with an aspect ratio of 16, there are 14 modes that need to be replaced.

That is, based on the illustration of FIG. 3, the numbering ranges for all angle patterns are-14 to 80, but the angle patterns are represented by the alternate method of Table 1 using consecutive numbers of 2-66.

In the embodiment of the application, the intra-frame pre-side device adopts the actual angle mode represented by the relative angle number when the angle mode configuration or identification is carried out; the relative angle numbers are sequentially represented in a prediction direction range corresponding to a preset width-height relationship, and a corresponding actual angle mode is sampled by adopting a preset angle sampling point from an initial angle; the starting angle is determined according to the prediction direction range corresponding to the width-height relation and the preset width-height relation of the processing block.

Specifically, the intra-frame pre-side device may determine the starting angle of the angle mode of the reference block according to the prediction direction range corresponding to the width-height relationship of the processing block and the preset width-height relationship; determining an angle offset range of a reference block based on a preset angle sampling point; and determining the actual angle mode corresponding to the processing block represented by the relative angle number according to the starting angle and the angle deviation range.

It should be noted that, in the embodiment of the present application, the wide-height relationship and the prediction direction range determine the starting angle. The prediction direction range represents what the angle pattern is of the preset angle sampling points selected from all the angle patterns. Wherein the prediction direction range is known in the prior art. Referring to table 1, for example, the 65 angular patterns with the range of directions 8-72 are predicted when the aspect ratio is 2.

In some embodiments of the present application, when the preset angle sampling point is 65, the relative angle numbers are consecutive numbers in a range from 2 'to 66', the actual angle patterns corresponding to the relative angle numbers are 65 consecutive actual angle patterns in a range from-14 to 80, and the selection of the 65 actual angle patterns is determined by a width-height relationship, where the relative angle numbers and the actual angle patterns are in one-to-one correspondence in sequence.

In the embodiment of the application, 2 '-66' is adopted to represent that the number of 2-66 is adopted to represent the actual angle mode corresponding to the relative angle. That is, the actual angle patterns indicated by consecutive numbers of the 2 '-66' range are 65 actual angle patterns of the corresponding 65 actual angles within the [ start value angle + angle deviation range lower limit value, start value angle + angle deviation range upper limit value ] angle range.

In the embodiment of the present application, the angular offset range is [ 0-the number of preset angular sampling points-1 ]. For example, when the preset angle sampling point is 65, the angle offset range is [0-64 ].

Exemplarily, in the embodiment of the present application, taking the preset angle sampling points, i.e. the number of the angle directions 65 as an example, the preset width-height relationship, the meaning of the start angle pattern represented by 2', the relative angle number, and the meaning of representing the actual angle pattern are shown in table 2.

TABLE 2

It is understood that in this way, referring to the actual angle pattern representation method in the L0279 proposal, the absolute numbers of all angle patterns are represented in the range [ -14,80], and only the 65 angle patterns, i.e. 65 angle numbers, which are continuous in the current coding block are included no matter what aspect ratio the current coding block has, and only the selection range (i.e. the prediction direction range) of the 65 angle patterns may be different according to the aspect ratio. In the representation method of the embodiment of the present application, the pattern from the lower left diagonal direction to the upper right diagonal direction is fixed to 2 '-66' (relative angle number) regardless of whether there is a wide angle pattern extension. However, the meaning of the actual angle pattern represented by the starting angle number of the relative angle number may be different due to different aspect ratios, and although the relative angle number ranges fall within the range of [ -14,80] due to the difference in the prediction direction ranges, the relative angle number ranges fall within the range of [ -14,80 ]. For example, in W/H ═ 2, the relative angle in the lower left diagonal direction is numbered 2', and what is actually characterized is the starting angle + the first value of the angular offset range: i.e. the actual angle pattern of 8+0 (the actual angle is characterized with the angle numbers of fig. 3); relative angle number 3 'characterizes the actual angle pattern of 8+1 (the second value of the angular offset range) (i.e. characterized pattern 9 in fig. 3), … …, and relative angle number 66' characterizes the actual angle pattern of 8+64 (the 65 th value of the angular offset range) (i.e. characterized pattern 72 in fig. 3).

The representation method of the embodiment of the application can avoid the deviation between the angle direction of the MPM list storage mode and the angle direction of the actual adjacent block caused by the representation by using the same angle mode number in the brightness prediction process. Meanwhile, the deviation between the borrowed brightness direction and the actual brightness direction at the center position of the current chroma block in the chroma prediction process is avoided.

It should be noted that, in the method for representing a relative angle number provided in this embodiment of the present application, during encoding, a code stream is put in a form of a syntax element for transmission, that is, the relative angle number is put in the code stream, and during decoding, a decoder has agreed meanings represented by the relative angle numbers with different aspect ratios, so that an actual angle mode corresponding to the relative angle number can be resolved through the received relative angle number.

In some embodiments of the present application, when the preset angle sampling point is 33, the relative angle numbers are consecutive numbers in a range from 2 'to 34', the actual angle patterns corresponding to the relative angle numbers are 33 consecutive actual angle patterns in a range from-7 to 41, and the selection of the 33 actual angle patterns is determined by a width-height relationship, where the relative angle numbers and the actual angle patterns correspond to each other one by one in sequence.

Exemplarily, in the embodiment of the present application, with the number of preset angle sampling points, that is, the number of angle directions being 33, the preset width-height relationship, the meaning of the start angle pattern characterized by 2', the relative angle number, and the meaning of the actual angle pattern are shown in table 3.

TABLE 3

In some embodiments of the present application, when the preset angle sampling point is 129, the relative angle number is a consecutive number in a range from 2 'to 130', the actual angle pattern corresponding to the relative angle number is 129 actual angle patterns consecutive in a range from-28 to 158, and the selection of the 129 actual angle patterns is determined by a width-height relationship, where the relative angle number and the actual angle patterns are in one-to-one correspondence in sequence.

Exemplarily, in the embodiment of the present application, with the number of preset angle sampling points, that is, the number of angle directions being 129, the preset width-height relationship, the meaning of the start angle pattern characterized by 2', the relative angle number, and the meaning of the actual angle pattern are shown in table 4.

TABLE 4

Reference block aspect ratio	Starting angle	Angular offset range	Actual angle mode
				W/H＝2	14	2’～130’	14～142
W/H＝4	22	2’～130’	22～150
				W/H＝8	26	2’～130’	26～154
W/H＝16	30	2’～130’	30～158
				W/H＝1	2	2’～130’	2～130
H/W＝2	-12	2’～130’	-12～118
				H/W＝4	-20	2’～130’	-20～110
H/W＝8	-24	2’～130’	-24～106
				H/W＝16	-28	2’～130’	-28～102

In the embodiment of the present application, the number of the preset angle sampling points is not limited.

An embodiment of the present application provides an intra prediction method, as shown in fig. 4, the method may include:

s101, obtaining a width-height relation of a reference block of a current block, a prediction direction range corresponding to a preset width-height relation and a preset angle sampling point.

S102, determining an actual angle mode corresponding to the reference block represented by the relative angle number according to the width-height relationship, the prediction direction range corresponding to the preset width-height relationship and the preset angle sampling point, so that the actual angle corresponds to the actual angle mode one by one.

S103, obtaining an angle prediction mode corresponding to the reference block based on the actual angle mode corresponding to the reference block.

And S104, performing intra-frame prediction on the current block based on the angle prediction mode.

In the embodiment of the present application, the reference block is a data block within a preset range where the current block is located and intra prediction is completed, and the reference block may be at least one reference block.

It should be noted that the intra prediction device includes at least one of the following when performing intra prediction: luma intra prediction and chroma intra prediction. The luminance intra-frame prediction uses neighboring blocks as reference blocks, and the luminance block where the center of the previous chrominance block is located can be used as the reference block in the chrominance intra-frame prediction. The chroma prediction modes may include DM, LM _ T, LM _ L, etc. modes.

In some embodiments of the present application, the prediction mode includes at least one of: a luminance intra prediction direction and a chrominance intra prediction direction.

It is to be understood that, when the prediction direction is a luminance intra prediction direction, the prediction direction of the reference block is a luminance direction, and for S104, when the current block is intra predicted, the luminance of the current block is actually intra predicted; similarly, when the prediction direction is the chrominance intra prediction direction, the prediction direction of the reference block is the chrominance direction, and for S104, when the current block is intra predicted, it is actually a process of intra predicting the chrominance of the current block.

In S101, no matter whether the intra-frame prediction device performs luminance intra-frame prediction or chrominance intra-frame prediction, in the process of obtaining the prediction mode of the current block, the intra-frame prediction device may obtain the width-height relationship of the reference block of the current block, the prediction direction range corresponding to the preset width-height relationship, and the preset angle sampling point.

In the embodiment of the present application, the aspect ratio of the reference block may be an aspect ratio, and the embodiment of the present application is not limited.

In the embodiment of the present application, a prediction direction range corresponding to the width-height relationship is preset: and aiming at different width-height relations of one processing block, obtaining an actual angle range containing the number of continuous preset angle sampling points from the lower left diagonal direction to the upper right diagonal direction.

In the embodiment of the present application, the number of the preset angle sampling points is the number of the sampling points from the lower left diagonal direction to the upper right diagonal direction.

It should be noted that the intra-frame prediction device may obtain the width-height relationship of the reference block of the current block and the prediction direction range corresponding to the preset width-height relationship, determine the preset angle sampling point in each prediction direction range, and select the relative angle number between the prediction direction and the start angle.

For example, 65 angular intra prediction modes are taken as an example for explanation. The prediction directions of the 65 angular intra prediction modes are defined as-135 degrees (mode 2) to 45 degrees (mode 66) in the clockwise direction, where [2 ', 66' ] is the relative angular number.

In the embodiment of the present application, under the condition that the number of the preset angle sampling points is certain, the lengths of the prediction direction ranges of all angle modes are the same, and no matter what width-height relationship the current block has, the current block only contains angles (i.e., relative angle numbers) of the number of the continuous preset angle sampling points, and the actual angle mode that only selects the number of the preset angle sampling points from the length of the prediction direction range is different due to the width-height relationship.

In S102, after the intra-frame prediction apparatus obtains the width-height relationship of the reference block of the current block, the prediction direction range corresponding to the preset width-height relationship, and the preset angle sampling point, the intra-frame prediction apparatus may determine, according to the width-height relationship, the prediction direction range corresponding to the preset width-height relationship, and the preset angle sampling point, the actual angle mode corresponding to the reference block represented by the relative angle number, so that the actual angle corresponds to the actual angle mode one to one, and the specific implementation is as follows: s1021-1023. The following were used:

and S1021, determining the initial angle of the angle mode of the reference block according to the width-height relation and the prediction direction range corresponding to the preset width-height relation.

And S1022, determining the angular offset range of the reference block based on the preset angular sampling point.

And S1023, determining an actual angle mode corresponding to the reference block indicated by the relative angle number according to the starting angle and the angle offset range.

After obtaining the prediction direction ranges corresponding to the width-height relationship and the preset width-height relationship, the intra-frame prediction device can determine the initial angle of the angle mode of the reference block from the prediction direction ranges corresponding to the preset width-height relationship according to the width-height relationship, and determine the angle offset range of the reference block based on the preset angle sampling point; and determining the actual angle mode corresponding to the reference block indicated by the relative angle number according to the starting angle and the angle deviation range, so that the intra-frame prediction device can select the actual angle mode in the angle deviation range indicated by the relative angle number by taking the starting angle as the starting point.

In some embodiments of the present application, the relative angle number may be used to represent the angle, so that the intra-frame prediction apparatus may determine the relative angle start number of the start angle of the angle mode of the reference block according to the width-height relationship and the prediction direction range corresponding to the preset width-height relationship; determining the angle offset range of the reference block as [ 0-the number of preset angle sampling points-1 ] based on the preset angle sampling points; and determining to sequentially represent the actual angle mode corresponding to the reference block by using continuous numbers in the range of the relative angle numbers [2 '-66' ]accordingto the starting code number and the angle offset range.

Exemplarily, in the embodiment of the present application, taking the preset angle sampling point as 65, that is, the number of the angle directions 65 as an example, the preset width-height relationship, the meaning of the start angle pattern represented by 2', the relative angle number, and the meaning of representing the actual angle pattern are shown in table 2.

TABLE 2

It will be appreciated that in this representation, referring to the actual angle pattern representation of fig. 3 in the L0279 proposal, the absolute numbers of all angle patterns are represented in the range [ -14,80], and only 65 angle numbers are included in succession regardless of the aspect ratio of the current coding block, except that the selection range of the 65 angle numbers may be different depending on the aspect ratio. In this new representation method, regardless of whether or not there is a wide-angle mode extension, the modes from the lower-left diagonal direction to the upper-right diagonal direction are represented by relative angle numbers 2 'to 66'. However, due to the different aspect ratios, the starting angular numbering of the angular patterns will be different, eventually making all angular numbering ranges fall within different intervals, but all within the range of [ -14,80 ]. For example, in W/H ═ 2, the relative angle in the lower left diagonal direction is numbered 2', and what is actually characterized is the starting angle + the first value of the angular offset range: i.e. the actual angle pattern of 8+0 (the actual angle is characterized with the angle numbers of fig. 3); relative angle number 3 'characterizes the actual angle pattern of 8+1 (the second value of the angular offset range) (i.e. characterized pattern 9 in fig. 3), … …, and relative angle number 66' characterizes the actual angle pattern of 8+64 (the 65 th value of the angular offset range) (i.e. characterized pattern 72 in fig. 3). The representation method of the embodiment of the application can avoid the deviation between the angle direction of the MPM list storage mode and the angle direction of the actual adjacent block caused by the representation by using the same angle mode number in the brightness prediction process. Meanwhile, the deviation between the borrowed brightness direction and the actual brightness direction at the center position of the current chroma block in the chroma prediction process is avoided.

It can be understood that the relative angle number is transmitted as a syntax element of the angle mode number in the code stream, so that the acquisition of the true prediction angle by the codec in the wide angle mode is simplified, and the improvement of the coding and decoding efficiency is facilitated.

TABLE 3

In some embodiments of the present application, when the preset angle sampling point is 129, the relative angle numbers are consecutive numbers in a range from 2 'to 130', the actual angle patterns corresponding to the relative angle numbers are 129 consecutive actual angle patterns in a range from-28 to 158, and the selection of the 129 actual angle patterns is determined by a width-height relationship, where the relative angle numbers and the actual angle patterns are in one-to-one correspondence in sequence.

TABLE 4

In S103, the intra prediction apparatus obtains an angular prediction mode corresponding to the reference block based on the actual angular mode corresponding to the reference block.

After obtaining the actual angular mode corresponding to the reference block, the intra prediction apparatus may use the actual angular mode to indicate the angular prediction mode (e.g., dirA, dirB) corresponding to the reference block.

That is, in the embodiment of the present application, the angle prediction mode corresponding to the reference block acquired by the intra prediction apparatus represents a one-to-one correspondence between the actual angle and the actual angle mode.

In S104, the intra prediction apparatus may intra predict the current block based on the angular prediction mode. Here, the intra prediction apparatus needs to construct a prediction mode list of the current block based on the angle prediction mode; and then, the intra-frame prediction of the current block is realized by adopting a prediction mode list.

In the embodiment of the present application, for luma intra prediction, the prediction mode list is an MPM list.

For chroma intra prediction, the prediction mode list is a DM list or an MDMS list.

For example, in luma intra prediction, as shown in fig. 5, a reference block is determined from all neighboring blocks above the current block and all neighboring blocks to the left of the current block, e.g., the neighboring blocks of the current block, left (L), top (a), Bottom Left (BL), top right (AR), and top left (AL), are taken as reference blocks in the reference block set. The derivation process of the MPM list considers the intra prediction modes (also referred to as intra prediction directions) of the 5 neighboring blocks of the current block, i.e., the left (L), upper (a), lower left (BL), upper right (AR), and upper left (AL) blocks.

The candidate prediction directions of the MPM list are divided into three groups: a neighbor prediction mode, a derived prediction mode, and a default prediction mode. First, a neighbor prediction mode is added in the MPM list. Each intra prediction mode in the MPM list can only be added once, i.e., no duplicate prediction modes can be included in the MPM list. And if the number of the prediction modes contained in the MPM list after the addition of the adjacent prediction modes is finished is less than 6, adding the derived intra-frame prediction mode into the MPM list. If the number of prediction modes included in the MPM list is less than 6 after the addition of the derived prediction mode is completed, adding a default prediction mode to the MPM list until an MPM list including 6 most probable intra prediction modes is derived.

When entropy coding is carried out on the intra-frame prediction mode of each brightness block, firstly, an MPM list of the brightness block is obtained, whether the intra-frame prediction mode selected by the brightness block is in the MPM list is judged, if the index number of the prediction mode in the MPM is binarized by using a truncated binary code, the smaller the index number is, the smaller the truncated binary code is generated, and then the truncated binary code is coded by an arithmetic coder, so that the bit overhead can be saved. If the intra prediction mode selected by the luminance block is one of the remaining 61 prediction modes not in the MPM list, the 61 prediction modes are numbered again from 0, and 16 prediction modes whose numbers are divisible by 4 are selected as the selection modes. If the intra prediction mode is in the selected mode, it is bypass coded using a fixed 4-bit length. If the intra prediction mode is relabeled again in the remaining 45 non-selection modes, it is binarized using a truncated binary code, a bit string of 5 or 6 bits in length is generated according to the number size, and then bypass encoding is performed.

Since the 6MPM list in JEM is more complex, a solution using a simplified 3MPM list has been proposed later. However, the 3MPM list includes a small number of prediction modes and the obtained prediction effect is not accurate enough, and then, it has been proposed to use a simplified 6MPM list (which is also the method used in the current VTM 3.0). For example, a new candidate prediction mode for the current block is constructed based on the prediction mode corresponding to the upper (a) block and the prediction mode corresponding to the left (L) block in fig. 5, and the MPM list is constructed as follows:

the reference line index used by the current block is 0:

when the prediction modes dirL, dirA of block L and block A are equal and neither is an angular mode, then

MPM { dirL, Planar/DC, HOR 18, VER 50, VER-4, VER +4 }; planar corresponds to 0, DC corresponds to 1, and there must be 6 modes in MPM. The adjacent pattern is plus or minus 1.

When the prediction modes of block L and block A are equal and both are angular, then

MPM＝{dirL,Planar/DC,dirL-1,dirL+1,dirL-2,dirL+2}；

When the prediction modes of block L and block A are not equal and both are angular, then

MPM＝{dirL,dirA,Planar/DC,max(dirL,dirA)-1,max(dirL,dirA)+1,max(dirL,dirA)-2}；

When the prediction modes of block L and block A are not equal and there is only one angular mode, then

MPM＝{dirL,dirA,Planar/DC,dirL-1,dirL+1,dirL-2}；

When the prediction modes of block L and block A are not equal and neither is the angular mode, then

MPM＝{dirL,dirA,HOR,VER,HOR-4,HOR+4}；

When the reference row index is 1 or 3:

when neither of the prediction modes dirL, dirA of block L and block A is an angular mode, then

MPM＝{VER,HOR,2,DIA,VDIA,26}；

When the prediction modes dirL, dirA of block L and block A are both angular, then

MPM＝{dirL,dirA,min(dirL,dirA)-1，min(dirL,dirA)+1，max(dirL,dirA)-1,max(dirL,dirA)+1,…}；

When there is an angle mode (denoted dir) in the prediction modes dirL, dirA of block L and block a, then MPM ═ dir, dir-1, dir +1, dir-1, dir +2, dir-3 };

in the embodiment of the present application, a method for constructing a chroma intra prediction direction of a DM, VVC draft 3 in chroma intra prediction is described as follows, as shown in table 5:

TABLE 5

For example, as shown in fig. 6, in an arrangement schematic diagram of a luminance block and a chrominance corresponding to a current block in the embodiment of the present application, as shown in fig. 6, a gray area of a left half of a right square is a currently processed chrominance block 71, a gray area of a left half of a left square is a luminance area corresponding to the currently processed chrominance block 71, and when intra prediction of the current chrominance block 71 is performed, a prediction direction recorded by using a center position of the luminance area is a prediction direction of a CR luminance block 701 in the right square of fig. 6.

Combining the contents shown in table 5 and fig. 6, it can be determined that if the prediction direction obtained by DM is the same as one of the latter four prediction directions, the same pattern of rows 3-6 is replaced with the prediction direction with index number 66.

MDMS is a more complex method for constructing chroma intra prediction direction, and as shown in table 6, compared with DM, MDMS has a 0.2% code rate saving, but has not been applied to VVC because of its too high complexity.

TABLE 6

As shown in fig. 7, the MDMS mode in table 6 is the intra prediction mode of the corresponding luminance block at five positions of the current chroma block center CR, upper left TL, upper right TR, lower left BL, and lower right BR, as shown in blocks 801 to 805 on the left side of fig. 7, and the chroma neighboring block mode in table 6 is the intra prediction direction of the chroma block space neighboring the left, upper left, lower left, upper right, and upper left blocks, i.e., the prediction direction of the written code stream, as shown in blocks 806 to 810 on the right side of fig. 7.

That is, in the embodiment of the present application, the intra prediction apparatus can perform both luminance intra prediction and chrominance intra prediction.

It can be understood that the angle patterns of all the rectangular blocks proposed in the present application sequentially represent the corresponding actual angle patterns after the initial angles and the angle deviation ranges are sequentially added, and are unified in a section within [ initial value angle + lower limit value of angle deviation range, initial value angle + upper limit value of angle deviation range ]. In the representation mode of the embodiment of the application, different initial angles are set according to different reference block width-height relationships, old angle mode numbers are used as meanings for representing new angle modes, the angle modes correspond to the angles in a one-to-one mode, so that the angle mode numbers of rectangular blocks with various width-height relationships are unified, the angle directions and actual angles expressed in a brightness MPM list and a chromaticity prediction DM are consistent, angle conversion under a wide angle mode is simplified, the meaning of an angle value represented by each mode is unified, deviation is eliminated, and the accuracy of intra-frame prediction is improved.

Furthermore, the angle offset number is transmitted as an angle mode number syntax element in the code stream, so that the acquisition of a real prediction angle by a coder-decoder in a wide angle mode is simplified, and the coding and decoding efficiency is improved.

Based on the foregoing implementation of the embodiments, an embodiment of the present application provides an intra prediction apparatus, including:

a configuration section configured to configure an actual angle pattern indicated by the relative angle number; the relative angle numbers sequentially represent the corresponding actual angle modes after sampling by adopting preset angle sampling points from an initial angle within a prediction direction range corresponding to a preset width-height relationship; the starting angle is determined according to the width-height relationship of the processing block and the prediction direction range corresponding to the preset width-height relationship, and the actual angles correspond to the actual angle modes one by one.

In some embodiments of the present application, when the preset angle sampling point is 65, the relative angle numbers are consecutive numbers in a range from 2 'to 66', the actual angle patterns corresponding to the relative angle numbers are 65 consecutive actual angle patterns in a range from-14 to 80, and the selection of the 65 actual angle patterns is determined by a width-height relationship, where the relative angle numbers and the actual angle patterns correspond to each other one by one in sequence.

In some embodiments of the present application, when the sampling of the preset angle sampling point is 33, the relative angle numbers are consecutive numbers in a range from 2 'to 34', the actual angle patterns corresponding to the relative angle numbers are 33 consecutive actual angle patterns in a range from-7 to 41, and the selection of the 33 actual angle patterns is determined by a width-height relationship, where the relative angle numbers and the actual angle patterns correspond to each other one by one in sequence.

In some embodiments of the present application, when the preset angle sampling point is 129, the relative angle number is a consecutive number in a range from 2 'to 130', the actual angle pattern corresponding to the relative angle number is 129 actual angle patterns consecutive in a range from-28 to 158, and the selection of the 129 actual angle patterns is determined by a width-height relationship, where the relative angle number and the actual angle patterns correspond to each other one by one in sequence.

Based on the foregoing implementation of the embodiment, as shown in fig. 8, an embodiment of the present application further provides an intra prediction apparatus 1, including:

an obtaining part 10 configured to obtain a width-height relationship of a reference block of a current block, a prediction direction range corresponding to a preset width-height relationship, and a preset angle sampling point;

the determining part 11 is configured to determine an actual angle mode corresponding to the reference block represented by the relative angle number according to the width-height relationship, the prediction direction range corresponding to the preset width-height relationship and the preset angle sampling point, so that the actual angle corresponds to the actual angle mode one by one;

the obtaining part 10 is further configured to obtain an angle prediction mode corresponding to the reference block based on the actual angle mode corresponding to the reference block;

an intra prediction part 12 configured to intra predict the current block based on the angular prediction mode.

In some embodiments of the present application, the determining part 11 is specifically configured to determine a starting angle of an angle mode of the reference block according to a prediction direction range corresponding to the width-height relationship and the preset width-height relationship; determining an angle offset range of the reference block based on the preset angle sampling point; and determining an actual angle mode corresponding to the reference block represented by the relative angle number according to the starting angle and the angle deviation range.

In some embodiments of the present application, the intra prediction part 12 is specifically configured to construct a prediction mode list of the current block based on the angular prediction mode; and adopting a prediction mode list to realize intra-frame prediction of the current block.

In some embodiments of the present application, the intra prediction includes at least one of: luma intra prediction and chroma intra prediction.

As shown in fig. 9, an embodiment of the present application further provides an intra prediction apparatus, including:

a processor 13, a memory 14 storing instructions executable by the processor 13 for intra prediction, and a communication bus 15 for connecting the processor 13 and the memory 14, the intra prediction instructions, when executed, implementing the intra prediction method described above.

In an embodiment of the present Application, the Processor 13 may be at least one of an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Digital Signal Processing Device (DSPD), a ProgRAMmable Logic Device (PLD), a Field ProgRAMmable Gate Array (FPGA), a Central Processing Unit (CPU), a controller, a microcontroller, and a microprocessor. It is understood that the electronic devices for implementing the above processor functions may be other devices, and the embodiments of the present application are not limited in particular. The intra-frame prediction apparatus may further include a Memory 14, the Memory 14 may be connected to the processor 13, wherein the Memory 14 is configured to store executable program codes, the program codes including computer operation instructions, and the Memory 14 may be a volatile Memory (volatile-Access Memory), such as a Random-Access Memory (RAM); or a non-volatile Memory (non-volatile Memory), such as a Read-Only Memory (ROM), a flash Memory (flash Memory), a Hard Disk (Hard Disk Drive, HDD) or a Solid-State Drive (SSD); or a combination of the above types of memories and provides instructions and data to the processor 13.

In the embodiment of the present application, a communication bus 15 is used to connect the processor 13 and the memory 14 and the intercommunication between these devices.

In addition, each functional module in this embodiment may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware or a form of a software functional module.

Based on the understanding that the technical solution of the present embodiment essentially or a part contributing to the prior art, or all or part of the technical solution, may be embodied in the form of a software product stored in a storage medium, and include several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute all or part of the steps of the method of the present embodiment. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Specifically, the intra-frame prediction instruction corresponding to one intra-frame prediction method in the present embodiment may be stored on a storage medium such as an optical disc, a hard disc, or a usb disk, and when the intra-frame prediction instruction corresponding to one intra-frame prediction method in the storage medium is read or executed by an electronic device, the method includes the following steps: acquiring a width-height relation, a preset width-height relation, a corresponding relation of a relative angle and a preset absolute angle range of a reference block of a current block; determining an actual angle mode corresponding to the reference block according to the width-height relationship, the corresponding relationship between the preset width-height relationship and the relative angle and the prediction absolute angle range, so that the actual angle and the actual angle mode are in one-to-one correspondence; obtaining an angle prediction mode corresponding to the reference block based on the actual angle mode corresponding to the reference block; intra-prediction is performed on the current block based on the angular prediction mode.

It can be understood that, in the intra-frame prediction process, the intra-frame prediction apparatus may process reference blocks with different width-height relationships in a manner of using a uniform actual angle mode, so that the actual angles correspond to the actual angle modes one to one, and thus, in the luminance prediction process and the chrominance prediction process, when a certain angle is represented, the angle mode of each shape block is specifically determined according to the aspect ratio, thereby simplifying angle conversion in the wide-angle mode, unifying the meaning of the angle value represented by each mode, eliminating deviation, effectively improving the accuracy of intra-frame prediction, and simultaneously improving the encoding and decoding efficiency.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of implementations of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart block or blocks and/or flowchart block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks in the flowchart and/or block diagram block or blocks.

The above description is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application.

Industrial applicability

The embodiment of the application provides an intra-frame prediction method and device and a computer storage medium, wherein the intra-frame prediction device can process reference blocks with different width-height relations in the intra-frame prediction process by adopting a uniform actual angle mode, so that the actual angles correspond to the actual angle modes one by one, and therefore, when a certain angle is represented in the luminance prediction process or the chrominance prediction process, the angle mode of each block in each shape is specifically determined according to the length-width ratio, the angle conversion in the wide-angle mode is simplified, the meaning of the angle value represented by each mode is unified, the deviation is eliminated, the accuracy of intra-frame prediction is effectively improved, and meanwhile, the coding and decoding efficiency is improved.

Claims

1. An intra prediction method applied to a decoder, the method comprising:

determining a plurality of neighboring blocks of a current block;

determining a first intra prediction mode of the plurality of neighboring blocks;

constructing an intra-prediction mode list for the current block according to the first intra-prediction modes of the plurality of neighboring blocks if the first intra-prediction mode is an angular intra-prediction mode;

determining a first intra prediction mode number of the current block according to the intra prediction mode list;

obtaining the aspect ratio of the current block, and mapping a first intra-frame prediction mode number of the current block to a second intra-frame prediction mode number under a wide-angle intra-frame prediction mode according to the aspect ratio;

and predicting the current block based on a target intra-frame prediction mode corresponding to the second intra-frame prediction mode number of the current block to obtain a prediction block.

2. The method of claim 1, wherein the method further comprises:

obtaining a reconstructed block of the plurality of neighboring blocks, wherein the reconstructed block is obtained by predicting based on a wide-angle intra prediction mode corresponding to the second intra prediction mode numbers of the plurality of neighboring blocks, and the second intra prediction mode numbers of the plurality of neighboring blocks are obtained by mapping a first intra prediction mode number of the plurality of neighboring blocks to an intra prediction mode number in the wide-angle prediction mode according to aspect ratios of the plurality of neighboring blocks;

and obtaining the prediction block according to the reconstruction blocks of the plurality of adjacent blocks based on the target intra-frame prediction mode corresponding to the second intra-frame prediction mode number of the current block.

3. The method of claim 1, wherein the plurality of neighboring blocks of the current block comprises at least one of a left neighboring block and an upper neighboring block corresponding to the current block.

4. The method of claim 3, wherein the method further comprises:

determining a maximum value and a minimum value of the first intra prediction mode of the plurality of neighboring blocks;

constructing the intra prediction mode list for the current block according to at least one of the first intra prediction modes of the plurality of neighboring blocks, the maximum value and the minimum value of the first intra prediction modes of the plurality of neighboring blocks.

5. The method of claim 4, wherein the method further comprises:

calculating at least one actual angular prediction mode with at least one of the first intra prediction modes of the plurality of neighboring blocks, the maximum value and the minimum value of the first intra prediction modes of the plurality of neighboring blocks as a relative angular prediction mode;

and constructing an intra-frame prediction mode list of the current block according to the at least one actual angle prediction mode.

6. The method of claim 5, wherein the method further comprises:

acquiring at least one actual angle prediction mode according to a preset deviation value and the relative angle prediction mode; wherein the preset offset value is 1 or 2.

7. The method of claim 6, wherein the method further comprises:

and calculating the sum or difference between the relative angle prediction mode and the preset offset value, and determining the at least one actual angle prediction mode according to the calculation result.

8. The method of any of claims 1-7, wherein mapping the first intra-prediction mode number of the current block to a second intra-prediction mode number in wide-angle intra-prediction mode according to the aspect ratio comprises:

determining the second intra-frame prediction mode number according to a first preset value and the first intra-frame prediction mode number under the condition that the width of the current block is larger than the height and the ratio of the width to the height is larger than or equal to 2;

and under the condition that the height of the current block is greater than the width and the ratio of the height to the width is greater than or equal to 2, determining the second intra-frame prediction mode number according to a second preset value and the first intra-frame prediction mode number.

9. The method of claim 8, wherein the mapping the first intra-prediction mode number to a second intra-prediction mode number in a wide-angle intra-prediction mode according to the aspect ratio is skipped if the width of the current block is equal to high.

10. The method of claim 8, wherein, in case the width of the current block is greater than the height and the ratio of width to height is greater than or equal to 2:

under the condition that the ratio of the width to the height is 2, if the value of the first intra-frame prediction mode number is less than 8, determining the second intra-frame prediction mode number according to the sum of the first intra-frame prediction mode number and a first preset value 65;

under the condition that the ratio of the width to the height is 4, if the value of the first intra-frame prediction mode number is less than 12, determining the second intra-frame prediction mode number according to the sum of the first intra-frame prediction mode number and the first preset value 65;

under the condition that the ratio of the width to the height is 8, if the value of the first intra-frame prediction mode number is less than 14, determining the second intra-frame prediction mode number according to the sum of the first intra-frame prediction mode number and the first preset value 65;

under the condition that the ratio of the width to the height is 16, if the value of the first intra-frame prediction mode number is less than 16, determining the second intra-frame prediction mode number according to the sum of the first intra-frame prediction mode number and the first preset value 65;

wherein, the value range of the second intra-frame prediction mode number is 8-80.

11. The method of claim 8, wherein, in case the height of the current block is greater than width and the ratio of the height and width is greater than or equal to 2:

under the condition that the ratio of the height to the width is 2, if the value of the first intra-frame prediction mode number is greater than 60, determining the second intra-frame prediction mode number according to the difference value between the first intra-frame prediction mode number and a second preset value 67;

under the condition that the ratio of the height to the width is 4, if the value of the first intra-frame prediction mode number is greater than 58, determining the second intra-frame prediction mode number according to the difference value between the first intra-frame prediction mode number and the second preset value 67;

under the condition that the ratio of the height to the width is 8, if the value of the first intra-frame prediction mode number is greater than 56, determining the second intra-frame prediction mode number according to the difference value between the first intra-frame prediction mode number and the second preset value 67;

under the condition that the ratio of the height to the width is 16, if the value of the first intra-frame prediction mode number is larger than 54, determining the second intra-frame prediction mode number according to the difference value between the first intra-frame prediction mode number and the second preset value 67;

wherein, the value range of the second intra-frame prediction mode number is-14-60.

12. The method of any one of claims 1-7,

in the case where the width of the current block is greater than the height, and the ratio of the width to the height is greater than or equal to 2, determining the second intra prediction mode number according to the following table:

in the case where the height of the current block is greater than the width and the ratio of the height and the width is greater than or equal to 2, determining the second intra prediction mode number according to the following table:

in each of the tables, the first intra prediction mode numbers are sequentially mapped to the second intra prediction mode numbers in a one-to-one correspondence.

13. An intra prediction method applied to an encoder, the method comprising:

determining a plurality of neighboring blocks of a current block;

14. The method of claim 13, wherein the method further comprises:

15. The method of claim 13, wherein the plurality of neighboring blocks of the current block comprises at least one of a left neighboring block and an upper neighboring block corresponding to the current block.

16. The method of claim 15, wherein the method further comprises:

17. The method of claim 16, wherein the method further comprises:

18. The method of claim 17, wherein the method further comprises:

19. The method of claim 17, wherein the method further comprises:

20. The method of any of claims 13-19, wherein mapping the first intra-prediction mode number of the current block to a second intra-prediction mode number in wide-angle intra-prediction mode according to the aspect ratio comprises:

21. The method of claim 20, wherein the mapping the first intra-prediction mode number to a second intra-prediction mode number in a wide-angle intra-prediction mode according to the aspect ratio is skipped if the width of the current block is equal to high.

22. The method of claim 20, wherein, in case the width of the current block is greater than the height and the ratio of width to height is greater than or equal to 2:

23. The method of claim 20, wherein, in case the height of the current block is greater than the width and the ratio of the height and the width is greater than or equal to 2:

24. The method of any one of claims 13-19,

25. A decoder, comprising:

a first determining module to determine a plurality of neighboring blocks to a current block and to determine a first intra prediction mode of the plurality of neighboring blocks;

a construction module for constructing an intra prediction mode list of the current block according to the first intra prediction modes of the plurality of neighboring blocks, if the first intra prediction mode is an angular intra prediction mode;

a second determining module for determining a first intra prediction mode number of the current block according to the intra prediction mode list;

a first obtaining module, configured to obtain an aspect ratio of the current block, and map a first intra-frame prediction mode number of the current block to a second intra-frame prediction mode number in a wide-angle intra-frame prediction mode according to the aspect ratio;

and the second obtaining module is used for predicting the current block based on a target intra-frame prediction mode corresponding to the second intra-frame prediction mode number of the current block to obtain a prediction block.

26. The decoder of claim 25, further comprising:

a third obtaining module, configured to obtain a reconstructed block of the plurality of neighboring blocks, where the reconstructed block is obtained by predicting based on a wide-angle intra prediction mode corresponding to the second intra prediction mode numbers of the plurality of neighboring blocks, and the second intra prediction mode numbers of the plurality of neighboring blocks are obtained by mapping a first intra prediction mode number of the plurality of neighboring blocks to an intra prediction mode number in the wide-angle prediction mode according to an aspect ratio of the plurality of neighboring blocks;

the second obtaining module is configured to obtain the prediction block according to the reconstructed blocks of the neighboring blocks based on the target intra-frame prediction mode corresponding to the second intra-frame prediction mode number of the current block.

27. The decoder of claim 25, wherein the plurality of neighboring blocks of the current block comprises at least one of a left neighboring block and an upper neighboring block corresponding to the current block.

28. The decoder of claim 27, wherein the construction module is further to:

29. The decoder of claim 28, wherein the construction module is further to:

30. The decoder of claim 29, wherein the construction module is further configured to:

31. The decoder of claim 30, wherein the construction module is further configured to:

32. The decoder according to any of claims 25-31, wherein the first obtaining module is further configured to:

33. The decoder of claim 32, wherein the first acquisition module is further configured to: in the case that the width of the current block is equal to the height, skipping the mapping of the first intra-prediction mode number to a second intra-prediction mode number in a wide-angle intra-prediction mode according to the aspect ratio.

34. The decoder of claim 32, wherein the first acquisition module is further configured to: in the case that the width of the current block is greater than the height and the ratio of width to height is greater than or equal to 2:

35. The decoder of claim 32, wherein the first acquisition module is further configured to: in the case that the height of the current block is greater than the width and the ratio of the height to the width is greater than or equal to 2:

36. The decoder according to any of claims 25-32, wherein the first obtaining module is further configured to:

37. An encoder, comprising:

38. The encoder of claim 37, further comprising:

39. The encoder of claim 37, wherein the plurality of neighboring blocks of the current block comprises at least one of a left neighboring block and an upper neighboring block corresponding to the current block.

40. The encoder of claim 39, wherein the construction module is further configured to:

41. The encoder of claim 40, wherein the construction module is further configured to:

42. The encoder of claim 41, wherein the construction module is further configured to:

43. The encoder of claim 41, wherein the construction module is further configured to:

44. The encoder according to any of claims 37-43, wherein the first obtaining module is further configured to:

45. The encoder of claim 44, wherein the first acquisition module is further configured to: in the case that the width of the current block is equal to the height, skipping the mapping of the first intra-prediction mode number to a second intra-prediction mode number in a wide-angle intra-prediction mode according to the aspect ratio.

46. The encoder of claim 44, wherein the first acquisition module is further configured to: in the case that the width of the current block is greater than the height and the ratio of width to height is greater than or equal to 2:

47. The encoder of claim 44, wherein the first acquisition module is further configured to: in the case that the height of the current block is greater than the width and the ratio of the height to the width is greater than or equal to 2:

48. The encoder according to any of claims 37-43, wherein the first obtaining module is further configured to:

49. A decoder comprising a processor, a memory storing instructions executable by the processor for intra prediction, and a communication bus connecting the processor and the memory, the intra prediction instructions when executed implementing the method of any of claims 1-12.

50. An encoder, comprising:

a processor, a memory storing processor-executable intra prediction instructions, and a communication bus connecting the processor and the memory, the intra prediction instructions when executed implement the method of any of claims 13-24.

51. A computer readable storage medium having intra-prediction instructions stored thereon, wherein the intra-prediction instructions, when executed by a processor, implement the method of any of claims 1-24.